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minute·timer

High intensity intervals

HIIT timer

Forty seconds hard, twenty seconds easy, eight rounds — loaded and ready. Change any of the three numbers and press start; the timer handles every switch after that.

00:40

Shortcuts: space start or pause · R reset · F fullscreen. The alarm rings even if you switch tabs.

In short

HIIT alternates near-maximal effort with incomplete recovery. What makes a session HIIT is intensity, not length: if you can talk in full sentences during the work phase, it is interval training rather than HIIT. This page opens at 40 seconds on, 20 seconds off, 8 rounds.

Default
40s work / 20s rest / 8 rounds
Beginner format
30s / 30s for 10 rounds
Session length
10 to 20 minutes of intervals, plus warm-up
Frequency
Two or three sessions a week alongside easier training

What makes an interval session HIIT

Intensity, not duration. The work phase has to be genuinely hard — near-maximal effort, the sort you could not hold for five minutes — with rest short enough that you never fully recover. That is what produces the training effect in a session that fits in fifteen minutes.

If you can talk in sentences during the work phase, it is interval training, but it is not HIIT. Neither is wrong; they just do different things.

Formats worth trying

WorkRestRoundsFeel
20s10s8Tabata, four brutal minutes
30s30s10Balanced, good for beginners
40s20s8The standard class format
60s60s6Long intervals, running or rowing

Be sensible about it

HIIT is demanding on the heart and on connective tissue. Warm up for at least five minutes, keep sessions to two or three a week alongside easier training, and stop if form falls apart — the last two rounds of a sloppy session are where injuries come from. If you are new to hard exercise or have a heart condition, talk to a doctor before starting.

Questions about the HIIT timer

How long should a HIIT session be?

Ten to twenty minutes of intervals is plenty for most people, on top of a warm-up and cool-down. If you can comfortably do forty minutes of it, the work phases are not hard enough.

Can I use it for running intervals outdoors?

Yes — the tones are the important part outdoors. Turn the volume up, put the phone in a pocket or armband, and listen for the switch rather than watching the screen.

How accurate is it?

Accurate to a fraction of a second over an hour. There is no rounding and no accumulated error, because each update recalculates the time left from scratch rather than subtracting from the last figure.

Do I need to sign up?

No. There are no accounts on this site at all, which also means there is nothing to store about you and nothing to delete later.

Sources

  1. Tabata, I. et al. (1996). Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO₂ max. Medicine & Science in Sports & Exercise, 28(10), 1327–1330.